Simulation is a mainstay of training in medicine, but has been restricted until quite recently to clinicians. With colleagues at Imperial College London, Roger Kneebone has developed “a lightweight inflatable operating theatre which can be set up almost anywhere. Prosthetic models recreate the look and the feel of human organs, even bleeding when you cut them. This allows people with no medical expertise to join a surgical team, taking part in operations performed by expert clinicians but with no risk of harming a real patient.